Typical studies of youth physical activity ignore the dependence among family members, examining only individual levels of data rather than individual and family levels. The current study examined physical activity among siblings (mean age = 12.2 years), using hierarchical linear modeling. Individual-and family-level covariates of physical activity were included in the model. Data from 930 siblings nested within 371 families were analyzed in a four-level multilevel design. Results indicated that siblings were similar in their levels of physical activity, and that levels of physical activity varied across families. At the individual level, age was a significant predictor of physical activity. At the family level, higher levels of family support were related to higher levels of sibling physical activity, as were single-parent status and higher income. Perceptions of neighborhood opportunities and observed neighborhood physical activity facilities were negatively related to family levels of physical activity.
The authors are with the Oregon Research Institute, 1715 Franklin Blvd., Eugene, OR 97403-1983.